Prehibernation swarming in temperate bats: a critical transition between summer activity and hibernation

Fraser, Erin E.; McGuire, L.

doi:10.1139/cjz-2022-0129

Cited by 9 publications

(9 citation statements)

References 123 publications

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“…Differences in seasonal behaviours could also contribute to observed response. In the fall, bats must put on sufficient fat reserves but are also engaged in fall swarm mating behaviours (Fraser & McGuire, 2023). In the spring, bats emerge from hibernation and females must recover their body condition and migrate to maternity roosts before giving birth (Norquay & Willis, 2014).…”

Section: (A) (B) (C)mentioning

confidence: 99%

Bats increased foraging activity at experimental prey patches near hibernacula

Frick

Dzal

Jonasson

et al. 2023

Ecol Sol and Evidence

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Emerging infectious diseases in wildlife can threaten vulnerable host populations. Actions targeting habitat improvements to aid population resilience and recovery may be beneficial long‐term strategies, yet testing the efficacy of such strategies before major conservation investments are made can be challenging. The disease white‐nose syndrome (WNS) has caused severe declines in several species of North American hibernating bats. We tested a novel conservation approach targeted at improving foraging conditions near bat hibernacula by experimentally manipulating insect density in the pre‐hibernation fattening period and spring emergence recovery period. We measured foraging (feeding buzzes) and echolocation activity of little brown bats Myotis lucifugus at ultraviolet (UV) light lures to determine behavioural response to augmented foraging conditions and characterized insect availability at UV light lures. In the fall, bat foraging activity was three times greater (95% CI: 1.5–5.8; p = 0.002) when UV lights were on, but there was no statistical support for differences in echolocation activity response when our experimental design alternated between nights with lights on and off. In the spring, we allowed UV light lures to run consistently each night and compared with a control location in similar habitat. Bat foraging activity was 8.5 times greater (95% CI: 4.5–16.0; p < 0.0001) and echolocation activity was 4.4 times higher (95% CI: 3.0–6.5; p < 0.0001) at UV light lures in the spring experiment. In both the fall and spring, UV light lures resulted in concentrated insect availability, attracting primarily moths (Order: Lepidoptera). In both seasons, nightly temperature had a strong influence on bat foraging, echolocation and insect activity. We show that a bat species threatened by WNS used enhanced foraging habitats near hibernacula during the critical pre‐ and post‐hibernation phases of their annual cycle. While light lures are unlikely to be a long‐term management strategy, our experiment provides initial evidence that bats behaviourally respond with increased foraging activity in areas with augmented insect prey availability. Our experimental results support developing management strategies focused on habitat protection, including restoration and enhancement of foraging habitats, in the immediate vicinity of bat hibernacula.

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Section: (A) (B) (C)mentioning

confidence: 99%

Bats increased foraging activity at experimental prey patches near hibernacula

Frick

Dzal

Jonasson

et al. 2023

Ecol Sol and Evidence

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“…Although we found that summer distributions are biased by sex, autumn pell-mell movements appear to be undertaken by both sexes (see Supporting Results section). We expect that male bats may be incentivized to search for mating opportunities at higher latitudes than their summering grounds, either by seeking mates directly or traveling to hypothesized lekking or swarming locations (22, 23, 59). Female bats must also be incentivized to move in late summer, potentially to either seek out or avoid mating events, or possibly to pursue optimal prey after an interval of low mobility while raising young.…”

Section: Discussionmentioning

confidence: 99%

Unusual migratory strategy a key factor driving interactions at wind energy facilities in at-risk bats

Campbell,

Nelson,

Nagel

et al. 2024

Preprint

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Seasonal movement strategies are poorly understood for most animals, impeding broader understanding of processes underlying migration and limiting practical conservation needs. Here we develop and implement a framework for integrating multiple sources of endogenous markers, in particular stable hydrogen isotope data, that capture and scale dynamics from the movements of individuals to that of continental migration. We assembled and integrated thousands of new isotopic measurements from bat fur with existing datasets and applied this framework to reveal migratory patterns of three broadly distributed bat species most at risk for fatalities at wind energy facilities. Our findings show that the species comprising the lowest proportion of wind turbine fatalities (silver-haired bats) exhibits expected movements to lower latitudes in autumn and higher latitudes in spring. Surprisingly, the two species with higher wind turbine fatality rates (hoary and eastern red bats) have more complex movements, including significant movement to higher latitudes during autumn. We term this unique strategy 'pell-mell' migration, during which some individuals are as likely to move to higher latitudes as lower latitudes, relative to their individual summering grounds, in early autumn, after which they move to similar or lower latitudes to overwinter. The pell-mell migratory period corresponds with peak fatalities at wind energy facilities, and bats moving northward during autumn are associated with mortality at those facilities. Our results provide direct support for the hypothesis that bat fatalities at wind energy facilities are related to migration and highlight the importance of migratory distance as an ultimate driver of increased interactions with wind energy facilities, which appears significantly greater for species that travel widely across latitudes in the autumn.

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“…In reality, immergence into hibernation and emergence from hibernation are not discrete in populations of hibernating bats. In both autumn and spring, bats likely use a mixed strategy with short bouts of torpor or hibernation interspersed with energy replenishing foraging (Fraser & McGuire, 2023). It is therefore more realistic to think of the winter season as a transition from summer behaviors as food becomes sporadic, into a deeper winter torpor, and then back into a transitory period as food becomes increasingly available in spring.…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Shifts in population density centers of a hibernating mammal driven by conflicting effects of climate change and disease

Boyles,

Brack,

Marshall

et al. 2023

Global Change Biology

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Populations wax and wane over time in response to an organism's interactions with abiotic and biotic forces. Numerous studies demonstrate that fluctuations in local populations can lead to shifts in relative population densities across the geographic range of a species over time. Fewer studies attempt to disentangle the causes of such shifts. Over four decades (1983–2022), we monitored populations of hibernating Indiana bats (Myotis sodalis) in two areas separated by ~110 km. The number of bats hibernating in the northern area increased from 1983 to 2011, while populations in the southern area remained relatively constant. We used simulation models and long‐term weather data to demonstrate the duration of time bats must rely on stored fat during hibernation has decreased in both areas over that period, but at a faster rate in the northern area. Likewise, increasing autumn and spring temperatures shortened the periods of sporadic prey (flying insect) availability at the beginning and end of hibernation. Climate change thus increased the viability of northern hibernacula for an increasing number of bats by decreasing energetic costs of hibernation. Then in 2011, white‐nose syndrome (WNS), a disease of hibernating bats that increases energetic costs of hibernation, was detected in the area. From 2011 to 2022, the population rapidly decreased in the northern area and increased in the southern area, completely reversing the northerly shift in population densities associated with climate change. Energy balance during hibernation is the singular link explaining the northerly shift under a changing climate and the southerly shift in response to a novel disease. Continued population persistence suggests that bats may mitigate many impacts of WNS by hibernating farther south, where insects are available longer each year.

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Prehibernation swarming in temperate bats: a critical transition between summer activity and hibernation

Cited by 9 publications

References 123 publications

Bats increased foraging activity at experimental prey patches near hibernacula

Bats increased foraging activity at experimental prey patches near hibernacula

Unusual migratory strategy a key factor driving interactions at wind energy facilities in at-risk bats

Shifts in population density centers of a hibernating mammal driven by conflicting effects of climate change and disease

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